1. Field of the Invention
The present invention generally relates to a bookbinding device connected to an image forming apparatus such as a copier, a printer, a facsimile machine, and a digital multifunction machine including at least two of those functions, a bookbinding method, and a recording medium including a bookbinding program.
2. Discussion of the Background
A finisher serially connected to an image forming apparatus such as a copier, a printer, a facsimile machine, and a digital multifunction machine including at least two of those functions can automatically perform post-processing, such as aligning, sorting, stapling, punching and/or bookbinding of sheets of recording media on which images are formed by the image forming apparatus.
Such finishers include a punch unit, a stapler, a bookbinding device, and the like. Bookbinding includes stitching an end portion or a center portion of a batch of sheets, attaching an adhesive tape to edges of the sheets, and punching an end portion of the sheets and then binding the sheets using a binder including metal or plastic rings or coils (hereinafter “ring binding”).
Several approaches described below have been proposed for such ring binding.
For example, one known technique aims to prevent binding failure caused by thermal expansion or deformation of plastic binders and uses a plastic binder (ring member) including multiple openably closeable rings attached to a bar at given regular intervals. As a hole is formed on each ring in a portion perpendicular to the bar, the binder is allowed to expand or shrink in a longitudinal direction thereof to a given extent. A ring-binding unit for binding sheet using this binder includes a binder holder provided with a registration unit that holds the rings of the binder at a given pitch. As the registration unit can adjust changes in a length of the binder even when the binder expands or shrinks due to changes in temperature, the pitch of the rings can match that of ring holes formed on the sheets, preventing binding failure.
Another known technique provides a sheet transport unit connected to a bookbinding device that binds sheets stacked on its sheet tray or sheets output from an image forming apparatus. The bookbinding device punches the sheets and/or binds the sheets using a ring binder. The sheet transport unit includes a table extending from inside the bookbinding device and a screw conveyor shaft that is provided on a side of the table extending in a longitudinal direction thereof and can engage the ring binders binding sheets. The screw conveyor shaft receives the sheets bound with the ring binder, and the ring binder engages the screw conveyor shaft as the screw conveyor shaft rotates. Then, the screw conveyor shaft transports the sheets bound with the ring binder to an end portion of the table in the longitudinal direction.
Another known method provides a finisher that is connected to an image forming apparatus and includes a punch unit that punches multiple different types of ring holes (punch holes) into the sheets output from the image forming apparatus. This punch unit can accommodate multiple different types of ring binders such as two-hole ring binders, three-hole ring binders, and the like. A control panel of the image forming apparatus includes a ring-hole selection part that displays ring-hole types that the punch unit accommodates. A user can select ring-hole type, and the selected ring-hole type is highlighted or displayed differently from another ring-hole that is not selected.
Different types of coils or ring members whose size and diameter are different are used depending on sheet size, the type of bookbinding, and the like. The number of rings and the intervals therebetween can differ as well depending on sheet size. Therefore, a ring member that is suitable for sheets to be bound together should be selected.
For example, if sheets are bound with a ring member whose size (length) does not match the size of the sheets, appearance of the bound sheets is not good even though the sheets can be bound together as long as intervals between the ring holes on the sheets match intervals between the rings of the ring member. If the size of the ring member is larger than a certain suitable size, the rings will protrude from the bound sheets.
When bookbinding is performed off-line, the user can immediately recognize whether or not the size of the ring member matches sheet size while setting the sheets on the image forming apparatus or the bookbinding device. However, known bookbinding systems are not provided with an input part via which the user can input the type of ring members, and accordingly the user must open the bookbinding device to visually check the type of the ring members set therein. Therefore, when bookbinding is performed online, that is, when printing, bookbinding, and discharging the bound sheets are performed automatically, malfunction might occur due to a discrepancy between the sheet size and the size of the ring member.
The type of ring member and the number of ring holes formed by the punch unit depend on sheet size as described above. Further, a length of a side to be bound (hereinafter “binding side”) of the sheets differs depending on sheet size. More specifically, a ring member suitable for a particular sheet size means that the following two conditions are satisfied: The number of the rings of the ring member is identical to a predetermined number of ring holes, and the length of the ring member fits the length of the binding side of the sheets. When these conditions are satisfied, intervals between the rings are identical to intervals between the ring holes formed on the sheets.
The above-described known methods do not disclose processing to be performed when the wrong type of ring member is set in an online bookbinding system, that is, when bookbinding is performed automatically on the sheets transported from the image forming apparatus. Accordingly, there is a need to manage such discrepancies between the type of ring members and sheet size in such an online bookbinding system.